The age of the mother is determined by the easily verified date when the pregnancy ends, not by the estimated date of conception.[2] Consequently, the statistics do not include women who first became pregnant before their 20th birthdays, if those pregnancies did not end until on or after their 20th birthdays.[2]

The highest rate of teenage pregnancy in the world — 143 per 1,000 girls aged 15–19 years — is in sub-Saharan Africa.[3] Women in Africa, in general, get married at much earlier ages than women elsewhere — leading to earlier pregnancies. In Nigeria, according to the Health and Demographic Survey in 1992, 47% of women aged 20–24 were married before 15 and 87% before 18. 53% of those surveyed also had given birth to a child before the age of 18.[4] Teenage birth rates in African countries (2002)[5] According to data from World Bank, as of 2015, the highest incidence of births among 15-19 years old girls was in: Niger, Mali, Angola, Guinea and Mozambique. [6]

A Save the Children report identified 10 countries where motherhood carried the most risks for young women and their babies. Of these, 9 were in sub-Saharan Africa, and Niger, Liberia, and Mali were the nations where girls were the most at-risk. In the 10 highest-risk nations, more than one in six teenage girls between the ages of 15 to 19 gave birth annually, and nearly one in seven babies born to these teenagers died before the age of one year.[7]

Surveys from Thailand have found that a significant minority of unmarried adolescents are sexually active. Although premarital sex is considered normal behavior for males, particularly with prostitutes, it is not always regarded as such for females. Most Thai youth reported that their first sexual experience, whether within or outside of marriage, was without contraception. The adolescent fertility rate in Thailand is relatively high at 60 per 1000. 25% of women admitted to hospitals in Thailand for complications of induced abortion are students. The Thai government has undertaken measures to inform the nation's youth about the prevention of sexually transmitted diseases and unplanned pregnancy.

The overall trend in Europe since 1970 has been a decrease in the total fertility rate, an increase in the age at which women experience their first birth, and a decrease in the number of births among teenagers.

The rates of teenage pregnancy may vary widely within a country. For instance, in the United Kingdom, the rate of adolescent pregnancy in 2002 was as high as 100.4 per 1000 among young women living in the London Borough of Lambeth, and as low as 20.2 per 1000 among residents in the Midlandslocal authority area of Rutland. In Italy, the teenage birth rate in central regions is only 3.3 per 1,000, but, in the Mezzogiorno it is 10.0 per 1000.

Teenage birth is often associated with economic and social issues: such as alcohol and drug misuse and, across 13 nations in the European Union, women who gave birth as teenagers were twice as likely to be living in poverty, compared with those who first gave birth when they were over 20.[11]

Romania and Bulgaria have some of the highest teenage birth rates in Europe. As of 2015, Bulgaria had a birth rate of 37/1.000 women aged 15-19, and Romania of 34.[12] Both countries also have very large Romani populations, who have an occurrence of teenage pregnancies well above the local average.[13][14][15]

In recent years, the number of teenage mothers is declining in Bulgaria.

The Netherlands has a low rate of births and abortions among teenagers (5 births per 1,000 women aged 15–19 in 2002[5]). Compared with countries with higher teenage birth rates, the Dutch have a higher average age at first intercourse and increased levels of contraceptive use (including the "double Dutch" method of using both a hormonal contraception method and a condom[citation needed]).

Nordic countries, such as Denmark and Sweden, also have low rates of teenage birth (both have 7 births per 1,000 women aged 15–19 in 2002[5]). However, Norway's birth rate is slightly higher (11 births per 1,000 women aged 15–19 in 2002[5]) and Iceland has a birth rate of 19 per 1,000 women aged 15–19 [5] (nearly the same as the UK). These countries have higher abortion rates than the Netherlands.[citation needed]

In some countries, such as Italy and Spain, the rate of adolescent pregnancy is low (6 births per 1,000 women aged 15–19 in 2002 in both countries).[5] These two countries also have low abortion rates (lower than Sweden and the other Nordic countries)[17] and their teenage pregnancy rates are among the lowest in Europe. However, Portugal, has a relatively high rate of teenage pregnancy (17 births per 1,000 women aged 15–19 in 2002).[5]

The UK has one of the highest teenage birth rates in Europe with a rate of 26.4 teenage births per 1,000 women aged 15–19 in 2006, down from 27.9 births in 2001.[18] The UK also has a higher rate of abortion than most European countries. Of young Britons reported engaging in sexual intercourse whilst in their teens, 80% said they did not use a form of contraception (Citation needed), although a half of those under 16, and one-third of those between 16 and 19, said they did not use a form of contraception during their first encounter (Citation needed). 10% of British teen mothers are married.[19] Adolescent pregnancy is viewed as a matter of concern by both the British government and the British press.

The Canadian teenage birth rate in 2002 was 16 per 1000 [5] and the teenage pregnancy rate was 33.9. According to data from Statistics Canada, the Canadian teenage pregnancy rate has trended towards a steady decline for both younger (15-17) and older (18-19) teens in the period between 1992-2002.[20] Canada's highest teen pregnancy rates occur in small towns located in rural parts of peninsular Ontario. Alberta and Quebec have high teen pregnancy rates as well.

In 2013, the teenage birth rate in the United States reached a historic low: 26.6 births per 1,000 women aged 15–19.[22] More than three-quarters of these births are to adult women aged 18 or 19.[22] In 2005 in the U.S., the majority (57%) of teen pregnancies resulted in a live birth, 27% ended in an induced abortion, and 16% in a fetal loss.[23]

The U.S. teen birth rate was 53 births per 1,000 women aged 15–19 in 2002,[5] the highest in the developed world.[11] If all pregnancies, including those that end in abortion or miscarriage, are taken into account, the total rate in 2000 was 75.4 pregnancies per 1,000 girls. Nevada and the District of Columbia have the highest teen pregnancy rates in the U.S., while North Dakota has the lowest.[24] Over 80% of teenage pregnancies in the U.S. are unintended;[25] approximately one third end in abortion, one third end in spontaneous miscarriage, and one third will continue their pregnancy and keep their baby.[26]

Within the United States teen pregnancy is often brought up in political discourse. The goal to limit teen pregnancy is shared by Republicans and Democrats, though avenues of reduction are usually different. Many Democrats cite teen pregnancy as proof of the continuing need for access to birth control and sexual education, while Republicans often cite a need for returning to conservative values, often including abstinence.

An inverse correlation has been noted between teen pregnancy rates and the quality of education in a state. A positive correlation, albeit weak, appears between a city's teen pregnancy rate and its average summer night temperature, especially in the Southern U.S. (Savageau, compiler, 1993–1995).

The birth rate for women aged 15–19 is one of the World Bank's World Development Indicators. The data for most countries and a variety of groupings (e.g. Sub-Saharan Africa or OECD members) are published regularly, and can be viewed or downloaded from a United Nations website.[27]

^ abKost K, Henshaw S, Carlin L (2010). "U.S. Teenage Pregnancies, Births and Abortions: National and State Trends and Trends by Race and Ethnicity"(PDF). Pregnancies are the sum of births, abortions and miscarriages. Please note that in these tables, “age” refers to the woman’s age when the pregnancy ended. Consequently, actual numbers of pregnancies that occurred among teenagers are higher than those reported here, because most of the women who conceived at age 19 had their births or abortions after they turned 20 and, thus, were not counted as teenagers.